The present invention relates to a current-limiting switching element, wherein for at least one contact set comprising a movable and a fixed contact member, a device for an auxiliary magnetic field is provided, the axis of which is arranged perpendicularly to the movable contact member.
An electric switch is known which shunts its operating current from main contacts to an auxiliary contact, the configuration of which can be interpreted as the arrangement described above (U.S. Pat. No. 2,555,799). The known arrangement is one of the many known devices in the category of arc traveling aids.
In current-limiting switching devices, rapid opening of contacts which sets in early is the most important requirement. In switching equipment this is achieved as a rule by a fast-acting magnet-armature system. Frequently, the magnet armature system strikes the movable contact member already before a switch latch is released. In order to accelerate the course of the arc, it is also customary to have electrodynamic forces act on the movable contact. Such measures are used at the same time as arc traveling aids. To this end, the effective magnetic field at the contact point is additionally magnified by iron yokes, iron plates or so-called blasting coils. Thereby, an arc can enter the quenching chamber more rapidly. The actual center of the magnetic-force generation, namely, the magnetic tripping device is as a rule relatively far removed from the contact point.